ASTM_D_3152_-_72_2000.pdf

Designation:D 3152 72(Reapproved 2000)An American National StandardStandard Test Method forCapillary-Moisture Relationships for Fine-Textured Soils byPressure-Membrane Apparatus1This standard is issued under the fixed designation D 3152;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the determination of capillary-moisture properties of fine-textured soils as indicated by themoisture content-moisture tension relationships determinedby pressure-membrane apparatus using tensions between 1 and15 atm(101 and 1520 kPa).Moisture tension(matrix suction)is defined as the equivalent negative gage pressure,or suction,in soil moisture.The test result is a moisture content which isa measure of the water retained in the soil subjected to a givensoil-water tension(or at an approximately equivalent heightabove the water table).NOTE1For determination of capillary-moisture relationships ofcoarse-and medium-textured soils,refer to Test Method D 2325.1.2 This standard does not purport to address all of thesafety problems,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:D 421 Practice for Dry Preparation of Soil Samples forParticle-Size Analysis and Determination of Soil Con-stants2D 698 Test Method for Laboratory Compaction Character-istics of Soil Using Standard Effort(12,400 ftlbf/ft3(600kNm/m3)2D 2325 Test Method for Capillary-Moisture Relationshipsfor Coarse-and Medium-Textured Soils by Porous-PlateApparatus23.Summary of Test Method3.1 Saturated soil samples are placed in contact with asaturated porous membrane resting on a screen disk installedwithin a high-pressure chamber.The bottom of the membrane-screen assembly is maintained at atmospheric pressure bymeans of a small drain tube or opening through the bottom ofthe pressure chamber.A desired air pressure admitted to thepressure chamber,and consequently to the top of the mem-brane,creates a pressure drop across the membrane.Thesaturated soil samples on the membrane establish equilibriumwith the water in the membrane.The water,held at a tensionless than the pressure drop across the membrane,will thenmove out of the soil,through the membrane,and out throughthe drain hose.When water has ceased to flow from the sampleand the membrane,indicating equilibrium for that particulartension,the moisture content of each sample is determined.Aseries of these tests at various tensions is required to prepare acomplete curve of the capillary-moisture properties for anyparticular soil.34.Apparatus(see Fig.1)4.1 Pressure-Membrane ChamberA pressure chamberconsisting of a space ring about 305 mm(12 in.)in diameterand about 13 mm(12in.),51 mm(2 in.),or 102 mm(4 in.)high,with heavy top and bottom steel plates 482 MPa(70 000psi)tensile strength;the top and bottom plates shall be heldtightly against O-ring gaskets on the spacer ring by heavy-duty58-in.bolts.Arubber diaphragm 1.6 mm(116in.)thick shall becemented to the top plate.NOTE2This equipment is available from several commercial firms.NOTE3Chamber should have safe pressure strength of 2.07 MPa(300psi).The test should be made in a constant-temperature room or cabinet,maintained at a temperature of 20C(68F),with a relative humidity of atleast 50%.4.2 Pressure SourceCompressed air or nitrogen in cylin-ders,or a high-pressure compressor.Nitrogen should be used ifsolutions extracted are to be analyzed chemically.4.3 Pressure ManifoldA U-tube containing 266 g ofmercury,used to maintain a pressure differential of about 28 67 kPa(4 6 1 psi).(See flow diagram and photograph in Fig.1.).4.4 Cellulose MembraneCellulose sausage case,usuallyseamless tubing about 6 m(20 ft)long and about 152 mm(6in.)wide.4.5 Sample Retainer RingsRigid plastic rings 10.2 mm(0.4 in.)in height and of 50.8 mm(2 in.)inside diameter,witha wall thickness of approximately 3.0 mm(0.12 in.),capable ofholding approximately 25 g of disturbed sample.Similar rings1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.04 on HydrologicProperties of Soil and Rock.Current edition approved Dec.29,1972.Published March 1972.2Annual Book of ASTM Standards,Vol 04.08.3This test method is modified from Richards,L.A.,1947,Pressure-MembraneApparatusConstruction and Use:Agricultural Engineering,Vol 28,pp.451454.1Copyright ASTM,100 Barr Harbor Drive,West Conshohocken,PA 19428-2959,United States.of other materials also may be used or undisturbed samplesmay be retained in sections of their sampler liners.The ringsare numbered in pairs;for example,A1